conda --download-only option error using a yaml file

I have tried various options to use the --download-only option, it works fine. When I use it without a yaml file

conda install -c esri --download-only arcgis=1.9.0

but if i use it with a yaml file:

conda env update --download-only --file c:/temp/arcgis/arcgis_package.yaml

usage:

conda-env-script.py [-h] {create,export,list,remove,update,config} ...

conda-env-script.py: error: unrecognized arguments: --download-only

yaml file:

name: arcgis-pro

channels:
  - conda-forge
  - defaults

dependencies:
  - pip
  - setuptools
  - wxpython=4.0.7.post2
  - cookiecutter
  - requests
  - cx_oracle
  - pillow
  - sqlalchemy
  - turbodbc
  - pymssql
  - pyodbc
  - pylint
  - beautifulsoup4
  - wheel
  - pycurl
  - feedparser
  - pywin32
  - six
  - pandas
  - numpy
  - paho-mqtt
  - skyfield